A method for transferring power between two DC circuits, each circuit being bipolar or connected at the midpoint thereof, involves: coupling the high voltage bus across a pair of inductors, arranged in parallel; coupling the low voltage bus across the pair of inductors; coupling the high voltage bus, the low voltage bus and the inductors by active switches and diodes, to provide for: (i) a storage configuration, wherein energy is transferred from one of the buses and stored in the inductors; and (ii) a release configuration, wherein energy is released from the inductors and transferred to the other of the buses.